Mount Marsili is a 3000-metre high seamount beneath the Tyrrhenian Sea, 150 km south-west of Naples. Marsili is active and recent research has indicated signs of restlessness (see this 2006 paper in PDF), although the risks of any dangerous eruptive activity are very slight). In an interview with the Italian newspaper Corriere della Sera, the director of the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Dr Enzo Boschi, has reminded everyone that Marsili is active and that there is a potential threat of an eruption/collapse generating a tsunami that would threaten Southern Italy:

It could happen tomorrow. The latest research says that the volcanic edifice is not strong and its walls are fragile. Furthermore we have measured the magma chamber that has formed in recent years and it is of large dimensions. All this tells us that the volcano is active and could erupt unexpectedly.

According to the article, observations indicate that hydrothermal emissions from vents around Marsili have become more intense recently, and evidence of landslides discovered by the oceanographic research vessel Urania last February ‘indicate an instability impossible to ignore’. Dr Boschi warns that a flank collapse at Marsili ‘would displace millions of cubic metres of material, which would be capable of generating a wave of great power’. Marsili is currently unmonitored, observes Dr Boschi: ‘A network of seismometers should be installed around the edifice, connected on land to a volcano monitoring centre. But this is beyond the budget’.

And it seems reasonable to suggest that the budget is what this article is actually all about. Despite the new attention this story will bring to Marsili as it gets cut-and-pasted around the web, there is nothing substantially new here, as Aldo Piombino notes in a very comprehensive post published on his blog today. No new activity lies behind this report, and nor has the potential threat, such as it is, changed in any way. The novelty, he observes, is in public attention being drawn to the need to monitor Marsili, which has been invisible in every sense as far as the Italian public is concerned.

Undersea volcanoes tend to be out of sight and out of mind. Writing in 2008, Aldo Piombino called Marsili ‘one of the least-known of the huge volcanic systems of Europe’, and argued that more attention must be paid to this active and potentially very destructive underwater giant:

It is statistically very unlikely that in our lifetimes we will see an explosion of Marsili, and even less likely that we will see a tsunami caused by a landslide on its flanks, but it is to be hoped that it will be placed under close seismic and geochemical surveillance, as with other active Italian volcanoes. I believe that it is necessary for civil protection and for science that one of the largest volcanoes in Europe is better understood.

Boris Behncke of the INGV discussed Marsili’s activity in the course of his Q&A on Dr Klemetti’s Eruptions blog last year, but also remarked that monitoring Marsili was not a priority for the INGV [UPDATE: in fact that is not what Boris meant. He meant that Marsili has not been a priority for the Italian authorities, Civil Defence, and the Italian public, rather than the INGV – see his comment at Eruptions]. Dr Boschi’s comments today would seem to indicate that that has changed. Aldo Piombino observes today that the technology is available within the INGV to monitor Marsili directly from the seabed using new broadband seismometers transmitting to land-based monitoring stations, and supports Dr Boschi’s call for full monitoring of the volcano. But that cannot happen without money, which is more likely to be forthcoming if the potential (and real but, it must be emphasized again, very remote) dangers of a tsunami-generating collapse at Marsili are stressed – hence the Corriere della Sera article.

So, it seems that a push has begun within Italian volcanology to get Marsili wired up for continuous and comprehensive monitoring. Let us hope it succeeds.

UPDATE 30 March 2010: Dr Erik Klemetti has more on Marsili at Eruptions, and Boris Behncke, himself of the INGV (Dr Boschi is Boris’s boss), has an illuminating comment here.

The Chilean newspaper El Mercurio has published a series of dramatic high-definition aerial photographs of the devastation caused along Chile’s coast by the tsunami associated with the 27 February 2010 earthquake.

Morne aux Diables is an 861-metre high stratovolcano at the northern tip of the island of Dominica in the eastern Caribbean. It is a little-known volcano: the Global Volcanism Program does not have an ‘eruptive history’ page for Morne aux Diables, noting that ‘No eruptions are known from Morne aux Diables in historical time’ but that ‘the volcano has a youthful appearance and activity at flank domes likely continued into the late-Pleistocene and Holocene’.

As discussed recently in these pages, a volcano does not have to erupt to be dangerous, and recent research by a team of geologists led by Dr Richard Teeuw of the University of Portsmouth concludes that Morne aux Diables may be very dangerous indeed. Geomorphological surveys by Dr Teeuw’s team and evidence from Google Earth3-D imaging have revealed that one flank of the volcano is in danger of collapse. If a flank collapse occurs at Morne aux Diables a tsunami could be triggered that would threaten the heavily-populated coast of Guadeloupe, 50 kilometres north of Dominica.

Dr Teeuw’s team plans to return to Dominica this summer, and again in 2010, to study the geomorphology of the volcano, and to survey the seafloor for evidence of previous collapses.

A couple of very interesting new geoblogosphere posts of strong volcanic interest:

Dike swarms and continental barcodes from Highly Allocthonous – the ‘magnetic barcodes’ of dikes in now separate continental fragments can be matched up, showing that at the time the dikes were created the fragments in question were in close enough proximity to be affected by the same episode of igneous intrusion.

Seven huge coral boulders standing on the western shore of Tonga’s main island Tongatapu may be evidence of a tsunami produced by a volcanic eruption, according to University of Texas researchers. The boulders, which are up to 9 metres high and weigh up to 1600 tonnes, are made of coral similar to that which makes up the offshore reefs of Tongatapu; their coral was formed about 122,000 years ago. They were clearly not formed in their present location and could not, on largely flat Tongatapu, have rolled downhill from somewhere else. The conclusion is that they were torn from the reef and hurled inland by a tsunami generated by a submarine eruption, probably from one of the volcanic centres in the northern section of the nearby Tonga-Kermadec Arc.

‘These could be the largest boulders displaced by a tsunami, worldwide’, says Matthew Hornbach of the University of Texas Institute for Geophysics. ‘We think studying erratic boulders is one way of getting better statistics on mega-tsunamis. There are a lot of places that have similar underwater volcanoes and people haven’t paid much attention to the threat’.

UPDATE: Dr Erik Klemetti at Eruptions takes a cautious look at the Tonga boulders: ‘it will be interesting to see what evidence they have for the deposit being from a volcanically-triggered event’.

UPDATE: National Geographic News has published an article on the Tonga boulders, which has been added to the list of links below.

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